3 Front-Panel Operation
94 Keysight E3633A and E3634A User’s Guide
To secure against calibration 
You can secure the power supply against calibration either from the front panel or 
over the remote interface. The power supply is secured when shipped from the 
factory, and the security code is set to “HP003633”
[1]
 or “HP003634”
[2]
.
Be sure to read the security code rules on page 90 before attempting to secure 
the power supply.
– Front-panel operation:
If the power supply is unsecured, you will see the above message for one 
second by holding   (Calibrate) key for 5 seconds when you turn on the 
power supply. To secure the power supply, press   (Secure) key after the 
“CAL MODE” message is displayed in the calibration mode, enter the security 
code using the control knob and resolution selection keys, and then press   
(Secure) key.
Notice that you should omit the “HP” and enter the remaining numbers as 
shown below.
When you press   (Secure) key to save the change, you will see the 
message below. The secured setting is stored in non-volatile memory, and 
does not change when power has been off or after a remote interface reset. To 
exit the calibration mode, turn the power off and on.
[1] For Keysight E3633A Model
[2] For Keysight E3634A Model
UNSECURED
000000 CODE
SECURED